Injection molded image sensor and a method for manufacturing the same

ABSTRACT

An injection molded image sensor includes metal sheets arranged in a matrix, an injection molded structure, a photosensitive chip, bonding pads, wires, and a transparent layer. Each metal sheet has a first board, a second board and a third board to form a -shaped structure. The injection molded structure encapsulates the metal sheets by way of injection molding and has a first molded body and a second molded body. The injection molded structure has a U-shaped structure and is formed with a cavity. The first, second, and third boards are exposed from top, bottom, side surfaces of the first molded body. The photosensitive chip is mounted within the cavity. The bonding pads are formed on the photosensitive chip. The wires electrically connect the bonding pads to signal input terminals of the first boards. The transparent layer covers over the first molded body to encapsulate the photosensitive chip.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an image sensor and a method for manufacturingthe same, and more particularly to an image sensor formed by way ofinjection molding.

2. Description of the Related Art

A general sensor is used for sensing signals, which may be optical oraudio signals. The sensor of the invention is used for receiving imagesignals or optical signals. After receiving image signals, the imagesensor converts the image signals into electrical signals, which arethen transmitted to a printed circuit board via a substrate.

Referring to FIG. 1, a conventional method for packaging an image sensorincludes the steps of:

providing a substrate 10 having an upper surface 11 formed with signalinput terminals 18 and a lower surface 13 formed with signal outputterminals 24;

providing a frame layer 12 on the substrate 10 to form a cavity 11together with the substrate 10;

providing a photosensitive chip 14 on the substrate 10 and within thecavity 11, a plurality of bonding pads 20 being formed on thephotosensitive chip 14;

providing a plurality of wires 16 for electrically connecting thebonding pads 20 of the photosensitive chip 14 to the signal inputterminals 18 of the substrate 10, respectively; and

providing a transparent layer 22, which is coated with an adhesive layer23, on the frame layer 12 for covering and encapsulating thephotosensitive chip 14.

The image sensor manufactured according to the above-mentioned methodhas the following drawbacks.

1. The image sensor has to be individually manufactured and cannot bemanufactured in mass production, so the cost thereof cannot bedecreased.

2. During the packaging processes, a substrate 10 has to be provided foreach package body, and then a frame layer 12 has to be adhered to thesubstrate 10. Therefore, the manufacturing processes are inconvenientand the material cost may be increased. In addition, the overflowedadhesive may influence the wire bonding process.

SUMMARY OF THE INVENTION

An object of the invention is to provide an injection molded imagesensor and a method for manufacturing the same, in which the massproduction may be achieved by way of injection molding and themanufacturing cost may be effectively decreased.

Another object of the invention is to provide an injection molded imagesensor and a method for manufacturing the same, in which a frame layerof the image sensor is formed by way of injection molding so that theoverflowed adhesive or glue cannot influence the wire bonding process.

Still another object of the invention is to provide an injection moldedimage sensor and a method for manufacturing the same, in which metalsheets serve as a substrate and traces thereon so that the manufacturingcost may be effectively decreased.

To achieve the above-mentioned objects, the invention provides aninjection molded image sensor for being electrically connected to aprinted circuit board. The image sensor includes a plurality of metalsheets arranged in a matrix, an injection molded structure, aphotosensitive chip, a plurality of bonding pads, a plurality of wires,and a transparent layer. Each metal sheet has a first board, a secondboard and a third board to form a -shaped structure. The injectionmolded structure encapsulates the metal sheets by way of injectionmolding and has a first molded body and a second molded body. Theinjection molded structure has a U-shaped structure and is formed with acavity. The first boards of the metal sheets are exposed from a topsurface of the first molded body to form signal input terminals, thesecond boards are exposed from a bottom surface of the first molded bodyto form signal output terminals, which are to be bonded to the printedcircuit board, and the third boards are exposed from a side surface ofthe first molded body. The photosensitive chip is mounted within thecavity of the injection molded structure. The bonding pads are formed onthe photosensitive chip. The wires electrically connect the bonding padsto the signal input terminals. The transparent layer covers over thefirst molded body to encapsulate the photosensitive chip.

To achieve the above-mentioned objects, the invention also provides amethod for manufacturing an injection molded image sensor. The methodincludes the steps of:

providing a plurality of metal sheets arranged in a matrix, each of themetal sheets having a first board, a second board and a third board toform a -shaped structure;

performing a first injection molding process to seal the metal sheetsand form a first molded body, wherein the first boards are exposed froma top surface of the first molded body to form signal input terminals,the second boards are exposed from a bottom surface of the first moldedbody to form signal output terminals, and the third boards are exposedfrom a side surface of the first molded body;

providing a connection board;

placing four first molded bodies around the connection board to form aU-shaped structure;

performing a second injection molding process to mold the first moldedbodies and the connection board into a second molded body so that thesecond molded body is combined with the first molded bodies and isformed with a cavity;

placing a photosensitive chip, on which a plurality of bonding pads isformed, within the cavity;

providing a plurality of wires for electrically connecting the bondingpads to the signal input terminals; and

placing a transparent layer over the first molded bodies to encapsulatethe photosensitive chip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic illustration showing a conventional image sensor.

FIG. 2 is a cross-sectional view showing an injection molded imagesensor of the invention.

FIG. 3 is a first schematic illustration showing the method formanufacturing the injection molded image sensor of the invention.

FIG. 4 is a second schematic illustration showing the method formanufacturing the injection molded image sensor of the invention.

FIG. 5 is a third schematic illustration showing the method formanufacturing the injection molded image sensor of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2, an injection molded image sensor of the inventionincludes a plurality of metal sheets 30 arranged in a matrix, aninjection molded structure 32, a photosensitive chip 34, a plurality ofwires 36 and a transparent layer 38.

Each metal sheet 30 has a first board 40, a second board 42 and a thirdboard 44 connecting the first board 40 to the second board 42.

The injection molded structure 32 is formed to encapsulate or seal themetal sheets 30 by way of injection molding so as to form a first moldedbody 50 and a second molded body 52. The injection molded structure 32is of a U-shaped structure and has a cavity 54. The first boards 40 areexposed from the top surface of the first molded body 50 to form signalinput terminals. The second boards 42 are exposed from the bottomsurface of the first molded body 50 to form signal output terminals,which are electrically connected to a printed circuit board 51 by thesolder tin 53 using the surface mount technique (SMT). The third boards44 are exposed from the side surface of the first molded body 50 so thatthe solder tin 53 may climb to the third board 44 during the SMT processfor stably mounting and bonding the metal sheets 30 to the printedcircuit board 51. In addition, a middle board 49 is arranged on thesecond molded body 52.

The photosensitive chip 34, which is arranged within the cavity 54 ofthe injection molded structure 32 and adhered to the middle board 49,has a plurality of bonding pads 56 thereon.

The wires 36 electrically connect the bonding pads 56 of thephotosensitive chip 34 to the signal input terminals formed at the firstboards 40 of the metal sheet 30, respectively. An adhesive layer 55 isapplied to connections between the wires 36 and the first boards 40 forprotect the wires 36.

The transparent layer 38 is mounted to the first molded body 50 with theadhesive layer 55 interposed therebetween to encapsulate or seal thephotosensitive chip 34.

Referring to FIGS. 3 and 2, a method for manufacturing the injectionmolded image sensor includes the following steps. First, a plurality ofmetal sheets 30 is provided. Each metal sheet 30 includes a first board40, a second board 42 and a third board 44, all of which form a “ shape”structure. Next, a first injection molding process is performed toencapsulate or seal each metal sheet 30 so as to form a first moldedbody 50. First engagement portions 58, which may be projections, areformed at edges of the first molded body 50. At this time, the firstboards 40 of the metal sheets 30 are exposed from the top surface of thefirst molded body 50 to form signal input terminals, the second boards42 are exposed from the bottom surface of the first molded body 50 toform signal output terminals, and the third boards 44 electricallyconnecting the first board 40 to the second board 42 are exposed fromthe side surface of the first molded body 50.

Then, as shown in FIGS. 2 and 4, a connection board 48 is provided.Second engagement portions 60, which may be slots, are formed atpositions corresponding to the first engagement portions 58 of the firstmolded body 50 so as to engage with the first molded body 50. Inaddition, the connection board 48 is also formed with a middle board 49.

As shown in FIG. 5, four first molded bodies 50 are arranged at theperiphery of the connection board 48 to form U-shaped sections.

Please refer again to FIG. 2. A second injection molding process isperformed to mold the connection board 48 and the first molded bodies 50into a second molded body 52, which is formed with a cavity 54 andcombined with the first molded bodies 50. The middle board 49 of theconnection board 48 is exposed from the second molded body 52 and ispositioned above the second molded body 52.

Then, a photosensitive chip 34, on which a plurality of bonding pads 56are formed, is placed within the cavity 54 and mounted to the middleboard 49.

Next, a plurality of wires 36 electrically connecting the bonding pads56 of the photosensitive chip 34 to the first boards 40 of the metalsheets 30 is provided to transmit signals from the photosensitive chip34 to the metal sheet 30.

Then, an adhesive layer 55 is applied to connections between the wires36 and the first boards 40 to protect the wires 36.

Next, a transparent layer 38 is adhered to the four first molded bodies50 by an adhesive layer 55 so that the photosensitive chip 34 may beencapsulated or sealed.

According to the above-mentioned method, when the image sensor issurface-mounted to the printed circuit board 51, the solder tin 53 mayclimb to the third boards 44 along the second boards 42 of the metalsheets 30 such that the image sensor may be firmly combined with andbonded to the printed circuit board 51.

According to the above-mentioned structure, the injection molded imagesensor and method of the invention has the following advantages.

1. A third board 44 is provided in each metal sheet 30 to connect thefirst board 40 to the second board 42 and is formed on the side surfaceof the first molded body 50. So, during the process for surface-mountingthe image sensor to the printed circuit board 51, the solder tin 53 mayclimb to the third board 44 such that the image sensor may be firmlycombined with and bonded to the printed circuit board.

2. Since the image sensors may be manufactured by way of injectionmolding, the manufacturing costs thereof may be effectively decreasedusing a mass production method.

3. Since the frame layer is formed by way of injection molding, it ispossible to prevent the glue or adhesive from overflowing.

4. Since the metal sheets 30 may serve as the conventional substrate andtraces thereon, the material and manufacturing costs may be effectivelydecreased.

While the invention has been described by way of examples and in termsof preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications. Therefore, the scope of theappended claims should be accorded the broadest interpretation so as toencompass all such modifications.

What is claimed is:
 1. An injection molded image sensor for beingelectrically connected to a printed circuit board, the image sensorcomprising: a plurality of metal sheets arranged in a matrix, each ofthe metal sheets having a first board, a second board and a third boardto form a -shaped structure; an injection molded structure forencapsulating the metal sheets by way of injection molding, theinjection molded structure having a first molded body and a secondmolded body, the injection molded structure having a U-shaped structureand being formed with a cavity, wherein the first boards of the metalsheets are exposed from a top surface of the first molded body to formsignal input terminals, the second boards are exposed from a bottomsurface of the first molded body to form signal output terminals, whichare to be bonded to the printed circuit board, and the third boards areexposed from a side surface of the first molded body; a photosensitivechip mounted within the cavity of the injection molded structure; aplurality of bonding pads formed on the photosensitive chip; a pluralityof wires for electrically connecting the bonding pads to the signalinput terminals; and a transparent layer covering over the first moldedbody to encapsulate the photosensitive chip.
 2. The image sensoraccording to claim 1, further comprising a middle board arranged on thesecond molded body, wherein the photosensitive chip is placed on themiddle board.
 3. The image sensor according to claim 1, furthercomprising an adhesive layer applied to connections between the firstboards and the wires to seal the wires.
 4. A method for manufacturing aninjection molded image sensor, comprising the steps of: providing aplurality of metal sheets arranged in a matrix, each of the metal sheetshaving a first board, a second board and a third board to form a -shapedstructure; performing a first injection molding process to seal themetal sheets and form a first molded body, wherein the first boards areexposed from a top surface of the first molded body to form signal inputterminals, the second boards are exposed from a bottom surface of thefirst molded body to form signal output terminals, and the third boardsare exposed from a side surface of the first molded body; providing aconnection board; placing four first molded bodies around the connectionboard to form a U-shaped structure; performing a second injectionmolding process to mold the first molded bodies and the connection boardinto a second molded body so that the second molded body is combinedwith the first molded bodies and is formed with a cavity; placing aphotosensitive chip, on which a plurality of bonding pads is formed,within the cavity; providing a plurality of wires for electricallyconnecting the bonding pads to the signal input terminals; and placing atransparent layer over the first molded bodies to encapsulate thephotosensitive chip.
 5. The method according to claim 4, furthercomprising: placing a middle board on the connection board and mountingthe photosensitive chip to the middle board.
 6. The method according toclaim 4, further comprising: forming a first engagement portion on thefirst molded body; and forming a second engagement portion on theconnection board so as to engage with the first engagement portion. 7.The method according to claim 6, wherein the first engagement portion isa projection, and the second engagement portion is a slot.
 8. The methodaccording to claim 4, further comprising applying an adhesive layer toconnections between the wires and the first boards so as to seal thewires.